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ON THE OCCURRENCE OF PERIDERM IN THE LEAVES OF WELWITSCHIA MIRABILIS

1967; Canadian Science Publishing; Volume: 45; Issue: 9 Linguagem: Inglês

10.1139/b67-150

1480-3305

R. Salema,

Plant Reproductive Biology

The study of leaves of different ages from 20 specimens of Welwitschia mirabilis from the desert of Moçamedes, Angola, has shown that periderm develops at the edge of the leaves a few centimeters from the base. This periderm was produced by cambial activity of mesophyll cells. Similar activity in periderm formation was also noted in other areas, notably between the vein and the lower epidermis, and later also in the region above the vein. Apparently the initiation of cambial activity was dependent upon the presence of a vascular bundle. The longitudinal splitting of the leaf occurs where there are areas of mesophyll cell breakdown and periderm formation crossing the leaf from one surface to the other.